Summary &c Conclusions -The limited stable storage available in mobile-computing environments can make traditional checkpointing and message logging unsuitable. Since storage on a mobile host is not considered stable, most protocols designed for these environments save the checkpoints on base stations. Previous approaches have assumed that the base station always has sufficient disk space for storing checkpoints. If there is not enough storage available, checkpoints might need to be aborted, This paper describes an adaptive protocol that manages storage for base stations. The protocol integrates leasing storage management -with a time-based coordinated checkpointing mechanism. The leasing enables storage managers to control disk-space effectively. Leasing prevents hanged processes from indefinitely retaining storage and, in addition, garbage collection is simple, Time-based checkpointing is integrated with leasing to reduce the number of messages for establishing consistent global states. The checkpointing mechanism uses a 3level storage hierarchy to improve checkpointing performance. Performance was evaluated by both implementation experiments and simulations. Tho results show that: • the adaptive protocol reduces checkpointing overhead, • the leasing mechanism maintains the desired storage assign- . ment for base stations.
All Science Journal Classification (ASJC) codes
- Safety, Risk, Reliability and Quality
- Electrical and Electronic Engineering